The FARCOS project

Collaboration: INFN (CT, LNS, MI, NA; Italy), GANIL (France), Un. Huelva (Spain)

Synergies: Fazia, Neutron detectors, Spectrometers, …

Physics case: dynamics and spectroscopy

1. Imaging in heavy-ion collisions

2. Spectroscopy of exotic nuclei:

– In heavy-ion collisions MPCS: Multi-Particle Correlation Spectroscopy

– Direct reactions

FARCOS: Femtoscope ARray for COrrelations and Spectroscopy

300 m

1500 m

Double-sided Silicon Strip

CsI(Tl) + D

32 x 32

32 x 32

6.4 x 6.4 cm2

4 cm

Angular resolution: ~0.2o at d=60 cm

Farcos as a modular correlator

Event characterization (4)

Correlations

Coupling to 4 detectors for dynamics studies (LNS, GANIL, NSCL-MSU, …)

Chimera @ INFN LNS

1m

1°

30°

TARGET

176°

Beam

1192 Si-CsI(Tl) Telescopes

SiCsI(Tl)

ΔE(Si)-E(CsI)

Charge Z for particles punching throught the Si detector

PSD in CsI(Tl)

Z and A for light charged particles

ΔE(Si)-ToF

Mass for particles stopping in the Si detector

E(Si)-Rise time

Charge Z for particle stopping in Si detectors (NEW)

ΔE(Si)-E(CsI)

Charge Z and A for light ions (Z<9) punching throught the Si detector

HI

pd

t

3He

LiBe

~300 μm

3-12 cm

Particle identification (as in Chimera)

V(t)t

slowfast

Farcos array features

• High angular resolution (<0.5o):

• Flexibility: allow coupling to

– 4 detectors, magnetic spectrometers, other correlators

– Neutron detectors for n-p correlations (future)

• Low thresholds for low energy experiments at Spiral2 and Spes

– pulse-shape on silicon and digitalization (future, interface to Fazia project)

Density dependence of the asymmetry term in nuclear EoS

E(, ) E , 0 Esym () 2 n p

n p

B.A. Li et al., Phys. Rep. 464, 113 (2008)???

Many approaches… large uncertaintiesMicroscopic many-body, phenomenological, variational

Symmetry Energy: who cares?

GDR & PYGMY RESONANCE

skins

halos

resonances

Supernovae, neutron stars

Lassa @ MSUImbalance ratios

FOPI @ GSIElliptic flow

Chimera @ LNSCompetitiion Inc. Fusion / DIC

• Isospin diffusion, fractionation, isoscaling phenomena…

Chimera@INFN, Indra@GANIL, Lassa@MSU, …

• n/p energy spectra and angular distributions

• p-p, n-n and n-p correlation functions

Producing density gradients

Large N/Z to enhance effects of Esym() 124Sn+124Sn (N/Z=1.48), 48Ca+48Ca (N/Z=1.4), 197Au+197Au (N/Z=1.49)

Radioactive beams…

Pre-equilibrium n,p Expansion Multifragmentation

Sec. decays!

Ebeam<100 MeV

n

p

Heavy-ion collisions: open issues

• Pre-equilibrium neutron/proton emissions: the most sensitive probes of Esym()

– n/p relative energy spectra– p-p, n-p, n-n two-particle correlation functions

• Space-time characterization: different particles emitted by several sources & over different time scales– Need space-time probes to disentangle sources

t as short as 10-22 sec

r as small as 1 fm“femtoscopy”

Correlation femtoscopy in HIC

d p

p

Femtoscope

p 1

p 2

1+R

(q) 1+

R(q)

q (MeV/c) q (MeV/c)

proton-proton deuteron-alpha

6Li

Sensitive to space-time properties

1p

1 R(q) k

Ycoin

p1,

p2

Yevt .mixing

p1,

p2

2p

q

rel

High angular resolution required!

ResonancesLow q (rel) measurements

Imaging correlations, “Femtoscopy”

Fast simultaneous emitting sources (pre-equilibium)

Source size

Slow sequential emissions (evap.)

14N+197Au E/A=75 MeV

G. Verde et al., PRC65, 069604 (2002)

q e

R(q) 4 dr r2 S(r)K (r,q)

Space-time images

Source function: Spatial distribution of proton emitting source in HIC: “femtoscopy” - measuring sizes r~1 fm and times t~10-21s

Farcos for complex particle correlations

r (fm)

S(r

)

Imagesd-

-6Lip-p

Different particles emitted by different sources and at different times (hierarchy)

Event characterization required ! ==> Coupling to 4 mandatory

p-p

1+R

(E* )

E*(MeV)

d-

6Li-

Multi-Particle Correlation Spectroscopy (MPCS)

Expansion

HIC and correlations as a spectroscopic tool

Several unbound species in just one single experiment!

10C*Not only EoS…

MPCS: 8B and 12C

Event mixingModified event mixing

3-alpha correlation function

12C states: sequential decay

C+Mg, E=53 MeV/u

F. G

renier et al., N

PA

2008Indra data

12C 12C Be

LASSA data

Spin of 8B states

W.T

an, PR

C 2004

J=1+

8B p+7Be

Accessing spins and branching ratios (sequential decay paths)

Multi- correlations: Hoyle and Boson condensate states

2 4 6 8 10 12 14

Ek (MeV)

1+R

(Ek)

2-2p correlations: states in 10C*

F. G

ren

ier, A

. Ch

bih

i, G. V

erd

e e

t al.,

Nu

cl. Ph

ys. A8

11

(20

08

) 23

3

p-p- four-particle correlations

10C 6Be+ (2p+)10C 8Be+p (+)p

10C 9B+p (+p)p

Disentangle sequential decay paths

10C

9B6Be

8Be

Symmetry energy and pp, nn and np correlations

Asy-stiff

Asy-soft

Symmetry potential

neutron-neutron

proton-proton

proton-neutron0.0

0.5

1.0

1.5

1

2

3

4

1

3

5

7

q (MeV/c)1+

R(q

)

52Ca+48Ca E/A=80 MeV

pp Sources

Asy-stiff: more localized source

Imaging

Future perspectives: pp, nn, np correlations! Coupling to neutron detectors

Neutron-proton correlation expts

neu

tro

n-p

roto

n

Ghetti et al, PRC 69 (2004) 031605Protons

Neutrons

Emission chronology sensitive to Asy-EOS

…difficult experiments

n/p experiments @ MSU

n detectorsLiquid scintillators

p detectorsDE-E (Lassa)

M. Famiano et al., PRL97, 052701 (2006)M.B. Tsang et al., PRL102, 122701 (2009)

112Sn+112Sn vs 124Sn+124Sn E/A=50 MeV

Esym () 0

n/p spectra ==> 0.7

Spectroscopy: “stand-alone” mode

Example:8He beam @ Spiral (GANIL) E/A=15.4 MeV8H + p 7He + d8H + p 6He + t

Shell structure close to drip lines

Similar experiments at LNS (FRIBS) or at LNL(SPES)

Spes: low energies (Pulse shape on 1st Silicon)

Must2 expts

Spectroscopy: “coupling” mode

FRIBS beams at the LNS of Catania

34Ar+p33Ar+dCorrelator (33Ar residue)

33Ar

34Ard

Chimera (d)

Correlator • Heavy core: Magnex at ~ 0o

• Scattered d with Correlator

• Spiral/Spiral2, Spes, …

Day-1 experiment at the INFN-LNS

Imaging correlations at low energies

• Perspectives at Spiral2 and Spes:

Imaging in fusion, fission, DIC, N/Z effects on limiting temperatures and reaction mechanisms, particle emission chronology

Requires low identification thresholds: pulse-shaping techniques on silicon detectors

• Chimera solution, Fazia implementation (digitalization of silicon signals)

• Future issue: Pulse-shape capabilities in integrated electronics (ASIC, etc.)

Workshop in 2011

• Catania, probably spring or early fall 2011– Integrated electronics for silicon detectors, new

solutions, pulse-shape in integrated solutions, coupling to different detectors (also neutrons, gammas, spectrometers, …), others

You are all very welcome: need to build up synergies